The present invention relates generally to logical volume management of a storage subsystem, especially for a network storage subsystem such as SAN (Storage Area Network) or NAS (Network Attached Storage), in a virtual machine environment.
Virtual Machine (VM) technology allows users to create virtual server machines onto physical server machines. Recently, many VM technologies use network storage subsystems such as SAN or NAS in order to store their data. For instance, using SAN for the VM environment allows each VM to move among physical server machines (e.g., VM-A can move from physical server machine-A to physical server machine-B).
Each VM has a virtual disk image such as a VMDK (Virtual Machine Disk Format) or VHD (Virtual Hard Disk) file. The physical server machine connects to the network storage subsystem which provides a LU (Logical Unit) to the physical server machine. A hyper visor program on the physical server machine creates a file system on the LU and creates a virtual image file such as a VMDK or a VHD file. Each VM can read from or write data into a virtual image file as if it were a physical disk image (a hyper visor program handles these processes; it provides disk I/O service to the VM using the virtual image file). Of course, each VM can connect to the physical disk (LU) on the network storage subsystem using RDM (Raw Device Mapping), iSCSI, or the like.
An administrator needs to manage the virtual/physical disk configuration. For instance, the administrator needs to know which physical disk (LU) is used by a specific VM-A or a specific virtual disk A. In another example, the administrator needs to manage the number of disks which are owned by VM-A, and so on.
VMFS (Virtual Machine File System) and RDM (Raw Device Mapping) allow the administrator to manage the virtual disk and VM. These management processes are performed by the hyper visor program on physical server machine.
These current solutions cover only the management of virtual disk and VM. However, each VM can also connect to a physical disk (LU) by using iSCSI, for instance. In that case, the administrator needs to manage not only the virtual disk but also the physical disk associated with a specific VM. Current solutions cannot address this problem.
There is no existing method to manage the virtual disk and physical disk together. This gives rise to data backup problems, for instance. When the administrator performs backup of the VM data, data consistency between or among multiple disks should be considered. This concept is referred to as “Consistency Group” (CGRP). CGRP allows multiple disks to have backup data simultaneously. For instance, application program-A uses disk-A, application program-B uses disk-B. Disk-A and Disk-B should be backed up because these disks have a relationship and have consistent data between the disks. The lack of a management method for both virtual and physical disks presents difficulties in addressing this kind of backup situation.